An improved practice for the production of coiled sheet metal strip material is described in U.S. Pat. Nos. 4,155,238, 4,170,691 and 4,173,313 granted May 22, 1979, Oct. 9, 1979 and Nov. 6, 1979, respectively, to John W. Rogers. According to this improved practice an elongated web of sheet metal is slit along parallel lines in a manner that produces parting lines containing intermittently spaced residuums of only partially sheared metal that bridge the parting line between adjacent strips and interconnect their facing edges. Thus, upon coiling of the slit product there results a wound construct containing a plurality of coiled strips integrally joined by frangible connections or tabs defined by the afore-mentioned partially sheared residuums of metal.
Detachment of individual strips from the construct can be effected by a breakaway device such as that described in U.S. patent application Ser. No. 898,001, now U.S. Pat. No. 4,191,318, to John W. Rogers filed Apr. 20, 1978, now U.S. Pat. No. 4,195,759, granted Apr. 1, 1980 in which all the interconnecting tabs in the parting line to be separated are fractured substantially simultaneously by the application of a shear force directly to the concerned strip coil. Separating coils in this manner requires great forces due to the requirement to break all the tabs substantially together. The magnitude of the forces that must be applied to the web material requires the use of heavy, expensive equipment. It furthermore places the material in danger of being damaged due to deformation of the coiled strip selected for removal or of the remaining construct.
The above problem is avoided, however, through the use of an alternate form of apparatus, such as that described in U.S. patent application Ser. No. 055,848 to John W. Rogers filed July 9, 1979 in which the tabs in each parting line to be severed are fractured sequentially by paying the concerned strip over a wedge-like body. Use of this apparatus significantly reduces the degree of force required to separate the strip; however, removal of the strip in coil form is precluded unless, of course, the payed out strip is subsequently rewound into a coil.
It is to an improved method of and apparatus for detaching coiled strips from a wound cluster, therefore, that the present invention is directed.